At one stage of a typical paper making operation a moving, continuous sheet of paper is passed, at high speed, over a plurality of dryer rolls and then through a stack of calender rolls which "calender" the paper by imparting the desired smooth finish thereto. Since it is difficult to guide the full width of the moving paper sheet off the last dryer roll and then feed it through the calender stack, a narrow "tail" is cut to one side of the moving sheet as it comes off the last dryer roll, the balance of the moving sheet being allowed to fall into a broke pit for reprocessing. The tail can be somewhat more easily fed through the calender stack and then used to draw the full width of the paper sheet through the calender stack.
In the prior art, a tail is typically cut in lightweight paper by directing a blast of compressed air at the moving paper sheet. This however produces a torn, ragged edge which can be difficult to pass through the infeed nips of the calender roll stack. Paper tails are typically produced in medium or heavier-weight paper sheets by hand-tearing which is dangerous procedure that has resulted in serious operator injuries.
The poorly cut paper tails produced by prior art methods are not only difficult to feed through the calender stack infeed nips, but also often overlap upon themselves. This poses serious problems because an overlapped tail may cause "roll bounce" when material of dual or greater thickness passes between the calender rolls. Over time, roll bounce may cause "barring", a form of marking of the calender rolls, which may eventually require expensive, time-consuming resurfacing of the rolls and consequential downtime of the paper making equipment.
A further disadvantage of the prior art is that the operating speed of the paper making equipment usually must be reduced while the tail is cut and transferred to the calender stack.
The present invention provides a paper tail cutter which cleanly cuts .Iadd.a smooth leading edge on .Iaddend.a tail from a moving sheet of paper and delivers the tail, at the full operating speed of the paper making equipment, to tail transfer equipment which guides the tail into the calender stack infeed nips, thereby vastly simplifying the tail handling and threading procedure and overcoming the foregoing difficulties by reducing equipment downtime and labour costs, while minimizing the potential for operator injuries.